Apparatus and methods related to constrained deployment of cryogenic balloons for limited cryogenic ablation of vessel walls

ABSTRACT

Embodiments related to cryogenically ablating a portion of the inner surface of a vessel by constraining a cryoballoon using various apparatuses and methods are disclosed. For example, a catheter can include a cryoballoon for ablation of the vessel wall and a constraining element disposed substantially in parallel with the cryoballoon to deflect or offset a portion of the cryoballoon away from non-target tissue of the vessel wall and prevent ablation of the non-target tissue. Partial circumferential, non-continuous, or helical ablation can be effective for treating a variety of renal, cardio-renal, and other diseases including but not limited to hypertension, heart failure, renal disease, renal failure, contrast nephropathy, arrhythmia, and myocardial infarction. The constraining element may be, for example, a second inflatable balloon or one or more self-expanding prongs.

CROSS REFERENCE TO RELATED APPLICATION

This disclosure claims the benefit of U.S. Provisional Application No.61/572,288, filed Apr. 25, 2011, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present technology relates in general to cryotherapy, and inparticular, to apparatus and methods for cryogenically cooling atargeted area of an inner surface of an anatomical vessel or othertissue.

BACKGROUND

Cryotherapy can be a useful treatment modality in a wide range ofcatheter-based interventional procedures. For example, cryotherapeuticcooling can be used to modulate nerves or affect other tissue proximateanatomical vessels (e.g., blood vessels, other body lumens, or otherareas in the body). This can reduce undesirable neural activity toachieve therapeutic benefits. Catheter-based neuromodulation utilizingcryotherapy can be used, for example, to modulate nerves and therebyreduce pain, local sympathetic activity, systemic sympathetic activity,associated pathologies, and other conditions. Furthermore, cryotherapycan be used, for example, for ablating tumors and treating stenosis. Insome cryotherapeutic procedures, it can be useful to deliver cryotherapyvia a balloon that can be expanded within an anatomical vessel. Suchballoons can be operatively connected to extracorporeal supportcomponents (e.g., refrigerant supplies). As the applicability ofcryotherapy for surgical intervention continues to expand, there is aneed for innovation in the associated devices, systems, and methods.Such innovation has the potential to further expand the role ofcryotherapy as a tool for improving the health of patients.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale. Instead, emphasis is placed on illustratingclearly the principles of the present technology.

FIG. 1 is a partially schematic isometric detail view of a commonlocation of neural fibers proximate an artery.

FIG. 2 is a partially schematic cross-sectional view of an artery havingan ablation assembly deployed therein, wherein the ablation assemblyincludes a cryoballoon and a constraining element that can position thecryoballoon within the artery.

FIG. 2A is a partially schematic illustration of an ablation therapypattern within an artery following treatment with the ablation assemblyof FIG. 2.

FIG. 3 is a side view of a dual balloon catheter having an ablationassembly at the distal end thereof, wherein the dual balloon catheterincludes a single guidewire lumen.

FIG. 3A is a cross-sectional view taken along line A-A of FIG. 3.

FIG. 3B is a cross-sectional view taken along line B-B of FIG. 3.

FIG. 3C is a sectional view taken along line C-C of FIG. 3.

FIG. 3D is a cross-sectional view taken along line D-D of FIG. 3.

FIG. 4 is a side view of a dual-balloon configuration of the ablationassembly of FIG. 3 according to another embodiment hereof.

FIG. 5 is a side view of a dual-balloon configuration of the ablationassembly of FIG. 3 according to another embodiment hereof.

FIG. 5A is a partially schematic cross-sectional view of an arteryhaving the ablation assembly of FIG. 5 deployed therein.

FIG. 6 is a sectional view taken along line C-C of FIG. 3 according toanother embodiment hereof, wherein the catheter further includes aninflation fluid return shaft for circulating warm inflation fluid withinthe constraining element of the ablation assembly.

FIG. 7 is a sectional view taken along line C-C of FIG. 3 according toanother embodiment hereof, wherein the catheter utilizes exhaust of thecryotherapy to inflate the constraining element of the ablationassembly.

FIG. 8 is a side view of a dual balloon catheter having an ablationassembly at the distal end thereof according to another embodimenthereof, wherein the dual balloon catheter includes two separateguidewire lumens.

FIG. 8A is a cross-sectional view taken along line A-A of FIG. 8.

FIG. 8B is a cross-sectional view taken along line B-B of FIG. 8.

FIG. 9 is a side view of a catheter assembly having an ablation assemblyat the distal end thereof according to another embodiment hereof,wherein the catheter assembly includes two balloon catheters.

FIG. 9A is a cross-sectional view taken along line A-A of FIG. 9.

FIG. 9B is a cross-sectional view taken along line B-B of FIG. 9.

FIG. 10 is a side view of the distal portion of FIG. 8 or FIG. 9,wherein the two balloons are joined via an adhesive.

FIG. 11 is a side view of the distal portion of FIG. 8 or FIG. 9,wherein the two balloons are located within an outer sheath.

FIG. 12 is a partially schematic cross-sectional view of an arteryhaving an ablation assembly according to another embodiment deployedtherein, wherein the ablation assembly includes a cryoballoon and aconstraining element that positions the cryoballoon within the artery.

FIG. 13 is a side view of a catheter having a ablation assembly at thedistal end thereof according to another embodiment hereof, wherein theablation assembly includes a cryoballoon and a pair of self-expandingprongs for deflecting at least a portion of the cryoballoon away fromthe vessel wall.

FIG. 13A is a side view of the distal portion of the catheter of FIG.13, wherein the cryoballoon is in an expanded or inflated configurationand the prongs are constrained within a sheath.

FIG. 13B is a side view of the distal portion of the catheter of FIG.13, wherein the cryoballoon is in an expanded or inflated configurationand the prongs are released from the sheath.

FIG. 13C is an illustrative perspective view of the distal portion ofthe catheter of FIG. 13 deployed within a vessel, wherein thecryoballoon is in an expanded or inflated configuration and the prongsare released from the sheath.

FIG. 14 is a side view of the prongs of FIG. 13, wherein the cryogenicballoon has been omitted for clarity and the prongs are in an expandedor deployed configuration.

FIG. 15 is a bottom view of the prongs of FIG. 13, wherein the cryogenicballoon has been omitted for clarity and the prongs are in an expandedor deployed configuration.

FIG. 16 is a side view of an alternative configuration of self-expandingprongs for deflecting at least a portion of the cryoballoon away fromthe vessel wall.

FIG. 17 is a side view of an alternative configuration of self-expandingprongs for deflecting at least a portion of the cryoballoon away fromthe vessel wall.

FIG. 18 is a side view of an alternative configuration of self-expandingprongs for deflecting at least a portion of the cryoballoon away fromthe vessel wall.

FIG. 19 is a side view of an alternative configuration of self-expandingprongs for deflecting at least a portion of the cryoballoon away fromthe vessel wall.

DETAILED DESCRIPTION

Specific embodiments of the present technology are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. The terms “distal” and“proximal” are used in the following description with respect to aposition or direction relative to the treating clinician. “Distal” and“distally” refer to positions distant from or in a direction away fromthe clinician. “Proximal” and “proximally” refer to positions near or ina direction toward the clinician.

The following detailed description discloses specific examples of thetechnology, but it is not intended to limit the present technology orthe application and uses of the present technology. For example,although the description discloses the present technology in the contextof treatment of blood vessels, such as renal arteries, the presenttechnology may also be used in any other body passageways or tissueswhere it is deemed useful. Furthermore, there is no intention to bebound by any expressed or implied theory presented herein.

In recent years, ablation of tissue has been used to modulate neuralfibers that contribute to renal function. Ablation may be accomplishedin various ways, including delivery of radio frequency (RF) energy,other suitable heating energies, or cryotherapy. Modulation of renalnerves is expected to be useful in treating a variety of renal,cardio-renal, and other diseases including heart failure, renal disease,renal failure, hypertension, contrast nephropathy, arrhythmia, andmyocardial infarction. Furthermore, renal neuromodulation is expected toreduce renal sympathetic nervous activity, which can increase removal ofwater and sodium from the body and return renin secretion to more normallevels. Normalized renin secretion can cause blood vessels supplying thekidneys to assume a steady state level of dilation and constrictioncorresponding to adequate renal blood flow.

In neuromodulation procedures, it may be desirable to performcircumferential ablation that extends continuously about a full 360° ofthe circumference of an anatomical vessel to positively affect a medicalcondition. For example, in the treatment of atrial fibrillation or otherarrhythmia, a circumferential treatment may be achieved by forming acircumferential lesion that is continuous completely about a normalcross-section of the pulmonary vein to disrupt aberrant electricalsignals. In the treatment of heart failure, a circumferential treatmentmay be achieved by forming a similar continuous circumferential lesionthat is continuous completely about a normal cross-section of a renalartery to reduce renal sympathetic neural activity. However, in somecases, it can be desirable to reduce structural changes to a bloodvessel and avoid a circumferential ablation lesion along a single radialplane or cross-section of a blood vessel. Partial circumferential,non-continuous, or helical ablation are expected to be effective totreat a variety of renal, cardio-renal, and other diseases includingthose listed herein with less structural changes to vessels than fullycircumferential, continuous, and non-helical ablation.

FIG. 1 illustrates a common anatomical arrangement of neural structuresrelative to body lumens or vascular structures, typically arteries.Neural fibers N generally may extend longitudinally along a lengthwiseor longitudinal dimension L of an artery A about a relatively smallrange of positions along the radial dimension r, often within theadventitia of the artery. The artery A has smooth muscle cells SMC thatsurround the arterial circumference and generally spiral around theangular dimension e of the artery, also within a relatively small rangeof positions along the radial dimension r. The smooth muscle cells SMCof the artery A accordingly have a lengthwise or longer dimensiongenerally extending transverse (i.e., non-parallel) to the lengthwisedimension of the blood vessel.

Neuromodulation may be accomplished by ablating tissue through the useof an ablation catheter. As utilized herein, the term ablation includesthe creation of scar tissue or a lesion that blocks or disrupts nerveconduction. In embodiments hereof, freezing temperatures or cryotherapycan be utilized to thermally damage or ablate target tissue of an arteryto achieve neuromodulation of the target neural fibers. As compared toablation lesions formed via radiofrequency energy, cryotherapy typicallyutilizes much less power to achieve neuromodulation. As described above,partial circumferential ablation (i.e., ablation extending around lessthan 360° of a vessel wall), non-continuous ablation, or helicalablation may be desirable in some cases. In order to form partialcircumferential, non-continuous, or helical ablation lesions,cryotherapy can be focused on or constrained to target regions of tissueto be treated and non-target tissue can be protected from ablation(e.g., by deflecting or offsetting a portion of a cryoballoon away fromthe non-target tissue using the various apparatuses and methodsdescribed herein).

Turning now to FIG. 2, an ablation assembly 200 is shown deployed withinan artery A. Ablation assembly 200 includes a cryoballoon 234 forneuromodulation of the target neural fibers and a constraining element236 that offsets cryoballoon 234 within the artery A. As will beexplained in more detail below, in various embodiments hereof,constraining element 236 can be a radially-expandable component thatexpands into contact with at least one of a portion of the exteriorsurface of cryoballoon 234 and a portion of the vessel wall to preventcryoballoon 234 from contacting and ablating non-targeted tissue of thevessel wall. Stated another way, constraining element 236 can deflectaway or block a portion of the surface of cryoballoon 234 fromcontacting non-targeted tissue of the vessel wall such that cryoballoon234 will contact a section of the vessel wall that corresponds to lessthan a full circumference of the vessel wall and thereby perform apartial circumferential ablation of a longitudinal section of the vesselwall. As shown in FIG. 2, in one embodiment constraining element 236 isa second balloon which pushes away or blocks a portion of cryoballoon234 from contacting non-target tissue of the vessel wall. Partialcircumferential, non-continuous, or helical ablation of artery A canalter the sympathetic nervous system and can be effective for treating avariety of renal, cardio-renal, and other diseases including but notlimited to hypertension, heart failure, renal disease, renal failure,contrast nephropathy, arrhythmia, and myocardial infarction.

A resulting cross-section of the ablation pattern or footprint ofablation assembly 200 is shown in FIG. 2A. The area of contact betweenthe exterior surface of cryoballoon 234 and the vessel wall may beconsidered a nominal treatment area, which is equal to or slightlysmaller than the ablation pattern resulting from ablation assembly 200because the ablation therapy may extend slightly beyond the borders ofthe nominal treatment area. For example, the nominal treatment area ofablation assembly 200 may extend around between 45° and 225° of thevessel wall circumference while the resulting ablation pattern ofablation assembly 200 may extend around between 10° and 340° of thevessel wall circumference. However, for purposes of the presentdisclosure, the nominal treatment area and the ablation pattern areconsidered to be approximately equal. The nominal treatmentarea/ablation pattern depends upon both a contact surface arc Ø of theablation assembly and a working length LW of cryoballoon 234 (see FIG. 3and FIG. 4 for examples of working lengths LW of a cryoballoon). Moreparticularly, the nominal treatment area/ablation pattern may becalculated by multiplying the length of the contact surface arc LØ bythe working length LW of cryoballoon 234. The length of contact surfacearc may be roughly calculated by the equation LØ=R((2{circumflex over( )}Ø)/360), wherein R is the radius and Ø is the contact surface arc.As previously mentioned, in embodiments hereof, constraining element 236can deflect or offset cryoballoon 234 from contacting non-targetedtissue such that the contact surface arc Ø of cryoballoon 234 isconstrained or limited to between 45° and 225° of the vessel wall.

The side view of FIG. 3 as well as the cross-sectional views FIG. 3A andFIG. 3B illustrate a first embodiment having an ablation assembly of acryoballoon and a second balloon for deflecting the cryoballoon awayfrom non-target tissue. More particularly, a dual balloon catheter 306includes an ablation assembly 300 at a distal end thereof. Ablationassembly 300 includes a first cryoballoon 334 and a second constrainingballoon 336 that are disposed substantially in parallel, i.e.,side-by-side, such that at least a portion of the exterior or outersurfaces of cryoballoon 334 and constraining balloon 336 are in contactin their expanded configurations. Balloons 334, 336 are shown in theirexpanded or inflated configurations in FIG. 3. For illustrative purposesonly, balloons 334, 336 as well as other dual balloon configurationsdescribed herein are shown in the figures as slightly separated fromeach other in their expanded configurations. However, it will beunderstood by those of ordinary skill in the art that at least a portionof the outer surfaces of balloons 334, 336 and all dual balloonconfigurations described herein typically press against and contact eachother when deployed in a vessel and constrained by the vessel wall asshown in FIG. 2. Balloons 334, 336 and other balloons disclosed hereincan be made using a variety of suitable manufacturing processes. Forexample, the balloons 334, 336 can be made using extrusion, molding, ora combination thereof. Furthermore, the balloons 334, 336 can be formedseparately or together. In some embodiments, when the balloons 334, 336are made of different materials (e.g., materials with differentcompliances), the different materials can be processed simultaneously(e.g., by coextrusion).

In the embodiment shown in FIGS. 3, 3A, and 3B, dual-balloon catheter306 has an over-the-wire (OTW) catheter configuration with an innerguidewire shaft 320 that defines a guidewire lumen 322 extendingsubstantially the entire length of the catheter for accommodating aguidewire 342. Catheter 306 includes a tubular component or outer shaft316 which defines a lumen 318. Outer shaft 316 has a proximal end 340that extends out of the patient and is coupled to a hub 308 and a distalend 341 coupled to proximal necks 315, 317 of balloons 334, 336,respectively. Distal necks 319, 321 of balloons 334, 336, respectively,are coupled to guidewire shaft 320. Proximal necks 315, 317 and distalnecks 319, 321 of balloons 334, 336 may be joined to outer cathetershaft 316 and guidewire shaft 320, respectively, in any conventionalmanner known to one of skill in the art of balloon catheterconstruction, such as by laser welding, adhesives, heat fusing, orultrasonic welding. In one embodiment, balloons 334, 336 are formed astwo separate components, the ends of proximal necks 315, 317 are joined,and the ends of distal necks 319, 321 are joined. Other suitablemanufacturing methods and configurations are also possible.

Guidewire shaft 320 has a proximal end (not shown) coupled to hub 308and a distal end 338 terminating distally of balloons 334, 336. Aproximal guidewire port 314 of hub 308 is in fluid communication withguidewire lumen 322 of guidewire shaft 320. Distal end 338 of guidewireshaft 320 may be coupled to a tapered distal catheter tip (not shown)that defines a distal guidewire port of the catheter. As shown in thesectional view of FIG. 3C, in one embodiment guidewire shaft 320 extendsthrough cryoballoon 334. However, it will be apparent to those ofordinary skill in the art that catheter 306 may be modified such thatguidewire shaft 320 alternatively extends through constraining balloon336. A single guidewire lumen can simplify catheter construction andluer design, as well as reduce the outer diameter of catheter 306. Inaddition, since distal necks 319, 321 of balloons 334, 336,respectively, are both coupled to guidewire shaft 320, the singleguidewire lumen catheter construction can help to maintain balloons 334,336 in position relative to each other during deployment.

Catheter 306 further includes a cryo-supply tube 324 extending throughouter shaft 316. The cryo-supply tube 324 defines an inflation lumen 326(see FIGS. 3A-3B) and has a proximal end (not shown) coupled to hub 308and a distal end 325 (see FIG. 3C) that terminates within cryoballoon334. A cryo-inflation port 310 of hub 308 is in fluid communication withinflation lumen 326 of cryo-supply tube 324. Cryo-supply tube 324receives and delivers a cryogenic agent such as N₂O liquid intocryoballoon 334 at a high pressure, e.g., 800 psi, such that there is apressure drop when the cryogenic agent enters the interior ofcryoballoon 334 and expands to a gas. The cryogenic agent may be anyliquid having a boiling point colder than approximately −10° C. atatmospheric pressure such as but not limited to N₂O liquid or CO₂liquid. During the phase change of the cryogenic agent, a cooling effecttakes place because expansion of compressed gas is an endothermicprocess that absorbs energy in the form of heat and thus results incooling of the surroundings. Accordingly, as the cryogenic agent expandsinto gas, cryoballoon 334 is expanded or inflated and the exteriorsurface of the cryoballoon is cooled to cryogenic temperatures operableto ablate or thermally damage tissue. The temperature of cryoballoon 334may be between approximately −5° C. and −120° C., which can result inmodulation of neural fibers located adjacent to cryoballoon 334. Aswould be understood by one of ordinary skill in the art of ballooncatheter design, hub 308 can provide a luer hub or other type of fittingthat may be connected to a source of inflation fluid and may be ofanother construction or configuration without departing from the scopeof the present technology.

Catheter 306 also includes a constraining-supply tube 328 extendingthrough outer shaft 316. The constraining-supply tube 328 defines aninflation lumen 330 and has a proximal end (not shown) coupled to hub308 and a distal end 327 (see FIG. 3C) that terminates withinconstraining balloon 336. An inflation port 312 of hub 308 is in fluidcommunication with inflation lumen 330 of constraining-supply tube 328.Constraining-supply tube 328 receives and delivers an inflation mediumsuch as saline or air into constraining balloon 336. Once inflated,constraining balloon 336 prevents a portion of the outer surface ofcryoballoon 334 from coming into contact with non-targeted tissue of thevessel wall. More particularly, constraining balloon 336 expands to pushaway or deflect a portion of the outer surface of cryoballoon 334 fromcontacting non-targeted tissue of the vessel wall. Non-targeted tissuemay thereby be prevented from contact with or protected from thecryogenically-cooled exterior surface of cryoballoon 334, and thereforeconstraining balloon 336 may prevent a complete continuouscircumferential ablation of the vessel wall.

In addition to offsetting cryoballoon 334, in one embodimentconstraining balloon 336 also serves to moderate the temperature of thecryotherapy. For example, when N₂O liquid is utilized as the cryogenicagent, the phase change of the cryogenic agent to gas may result in acryoballoon temperature in the range of −70° C. to −80° C. However,neuromodulation may be accomplished at temperatures between −10° C. and−40° C., and these higher temperatures may be preferred in certainapplications to minimize unnecessary damage to the vessel. Sincecryoballoon 334 and constraining balloon 336 deploy and expand againsteach other within the artery during treatment, heat transfer can occurtherebetween. Accordingly, an inflation fluid such as water or salinewithin constraining balloon 336 may freeze. However, the decrease inresulting temperature will not be to such an extent that thermal injurywill occur. Thermal injury or neuromodulation generally occurs attemperatures below −5° C., while a frozen constraining balloon 336 canhave a temperature at or above −3° C. Notably, the heat transfer fromconstraining balloon 336 to cryoballoon 334 may be beneficial toincrease the temperature of the cryogenically-cooled balloon outersurface from, e.g., −80° C., to a preferred temperature for ablation,e.g., between −10° C. and −40° C. Thus, the heat transfer between theballoons may help to moderate the temperatures of the cryotherapy.

In one embodiment, balloons 334, 336 are inflated simultaneously. Inanother embodiment, constraining balloon 336 and cryoballoon 334 areinflated sequentially. Constraining balloon 336 may be inflated prior tocryoballoon 334 in order to properly position and/or orient the balloonswithin the artery.

The multiple catheter shafts of catheter 306, e.g., outer shaft 316,guidewire shaft 320, cryo-supply tube 324, and constraining-supply tube328, may be formed of a polymeric material, non-exhaustive examples ofwhich include polyethylene, polyethylene block amide copolymer (PEBA),polyamide, and/or combinations thereof, which can be laminated, blended,co-extruded, or processed according to another suitable method. In anembodiment, guidewire shaft 320 may be a flexible tube of a polymericmaterial, such as, e.g., polyethylene tubing. Optionally, outer shaft316 or some portion thereof may be formed as a composite having areinforcement material incorporated within a polymeric body in order toenhance strength and/or flexibility. Suitable reinforcement layers caninclude braiding, wire mesh layers, embedded axial wires, embeddedhelical or circumferential wires, and the like. In one embodiment, forexample, at least a proximal portion of outer shaft 316 may be formedfrom a reinforced polymeric tube. In addition, although catheter 306 isdescribed herein as being constructed with various shafts extendingtherethrough for forming lumens of the catheter, it will be understoodby those of ordinary skill in the art that other types of catheterconstruction are also possible, such as, without limitation thereto, acatheter shaft formed by multi-lumen profile extrusion. In anotherembodiment, catheter 306 may be modified to be of a rapid exchange (RX)catheter configuration without departing from the scope of the presenttechnology such that guidewire shaft 320 extends within only the distalportion of catheter 306.

Although shown as having approximately equal expanded profiles, thecryoballoon and the constraining balloon may have different, unequaldimensions depending on the desired ablation therapy pattern. Forexample, as shown in the embodiment of FIG. 4, an ablation assembly 400can include a cryoballoon 434 which is shorter in length than aconstraining balloon 436. As described above in more detail, the nominaltreatment area/ablation pattern can depend upon the working length LW ofthe cryoballoon. Accordingly, in general, shorter cryoballoon 434contacts less tissue in the longitudinal direction of the vessel wallthan cryoballoon 334 and thus results in a smaller nominal treatmentarea than cryoballoon 334. In addition, shorter cryoballoon 434 mayrequire a longer treatment time in order to achieve neuromodulation asopposed to longer cryoballoons which may cause deeper and/or longerablation patterns.

In another example, the cryoballoon and the constraining balloon mayhave different expanded outer diameters. In the embodiment of FIG. 5, anablation assembly 500 can include a cryoballoon 534 having a smallerexpanded outer diameter than a constraining balloon 536. To achievedifferent expanded outer diameters, the balloons may be formed ofmaterials having different compliances. Dilatation balloons may beclassified, for example, as being compliant, noncompliant, orsemi-compliant. Compliant balloons can be characterized by their abilityto radially expand beyond their nominal diameters in response toincreasing inflation pressure. Such balloons can be said to follow astress-strain curve obtained by plotting balloon diameter versusinflation pressure. Noncompliant balloons can be characterized by nearlyflat stress-strain curves illustrating that the balloon diameters expandrelatively little over the range of usable inflation pressures. Toachieve a smaller expanded outer diameter, cryoballoon 534 may besemi-compliant or non-compliant. In some embodiments, cryoballoon 534can be 10% or less compliant and formed from PEBAX polymer or nylon.Constraining balloon 536 may be, for example, between 50% and 100%compliant and formed from polyurethane or silicone. Percentagecompliance can correspond to the percentage of expansion that occursbetween the cryoballoon 534 at an operating pressure and the cryoballoon534 at a rated pressure (e.g., a burst pressure or a maximum inflationpressure). The recited values for percentage compliance can also applyto dispensability, which can be calculated as follows:

${Distensibility} = {\lbrack {\frac{{Diameter}\mspace{14mu}{of}\mspace{14mu}{Balloon}\mspace{14mu}{at}\mspace{14mu}{Selected}\mspace{14mu}{Pressure}}{{Nominal}\mspace{14mu}{Diameter}\mspace{14mu}{of}\mspace{14mu}{Balloon}} - 1} \rbrack \times 100\%}$The selected pressure can be an arbitrary, relatively high pressure(e.g., 10 bar). Suitable materials that may be utilized to achieve adesired amount of compliance for the balloons include but are notlimited to polymers such as polyethylene, polyethylene block amidecopolymer (PEBA), PEBAX polymer, nylon, silicone, polyethyleneterephthalate (PET), polyamide, polyurethane, and copolymers or blendsthereof.

As shown in FIG. 5A, during deployment within artery A, constrainingballoon 536 of a greater expanded outer diameter can essentially wrap orcurl around smaller cryoballoon 534, thereby preventing ablation of agreater circumferential portion of the vessel wall. Stated another way,the constraining balloon 536 can curl around smaller cryoballoon 534 andeffectively reduce the contact surface arc Ø of the nominal treatmentarea/ablation pattern. The expanded diameter of cryoballoon 534determines the contact surface arc Ø and therefore determines the amountof circumferential tissue cryogenically ablated. In general, smallercryoballoon 534 contacts less tissue around the circumference of thevessel wall and thus results in a smaller nominal treatmentarea/ablation pattern than cryoballoon 334. In the embodiment depictedin FIG. 5A, contact surface arc Ø is less than half of the circumferenceof the vessel wall or between 45° and 180° of the vessel wall. Inanother embodiment (not shown), if it is desired to ablate more thanhalf of the circumference of the vessel wall, the cryogenic balloon canhave a contact surface arc Ø between 180° and 225° of the vessel walland may be constructed to have a greater expanded outer diameter thanthe constraining balloon such that the larger cryoballoon wraps aroundthe smaller constraining balloon during deployment.

Referring back to FIG. 3 as well as the sectional views of FIG. 3B, FIG.3C, and FIG. 3D, another feature of catheter 306 is described. In theembodiment of FIG. 3, constraining balloon 336 can be inflated and heldat a constant pressure or at a constant outer diameter depending on thedesign thereof and an interior of constraining balloon 336 is not influid communication with lumen 318 of outer shaft 316. As shown in thecross-sectional view of FIG. 3B which is taken at the location of aproximal bond 329 between balloon necks 315, 317 of balloons 334, 336,respectively, proximal bond 329 surrounds and seals offconstraining-supply tube 328 from lumen 318 of outer shaft 316. At thesite of proximal bond 329, outer shaft 316 transforms from the annularconfiguration of FIG. 3A to a generally figure “8” configuration whichresembles balloon necks 315, 317. In one embodiment, proximal balloonneck 315 of cryoballoon 334 has a larger diameter and correspondinglumen than proximal balloon neck 317 of constraining balloon 336 inorder to allow expanded cryogenic gas or exhaust to exit from theinterior of cryoballoon 334 as will be explained in more detail herein.Although proximal balloon neck 315 may be larger than proximal balloonneck 317, the expanded outer diameters of balloons 334, 336 may be thesame or different as described above. Proximal bond 329 may be formed inany suitable manner known in the art, including via an adhesive and/orheat fuse.

In contrast to constraining-supply tube 328, cryo-supply tube 324 andguidewire shaft 320 extend freely through, e.g., are not bonded to,outer shaft 316 and into balloon neck 315 of cryoballoon 334. As notedabove and with reference to FIG. 3C, a continuous supply of cryofluidexits distal end 325 of cryo-supply tube 324 into the interior ofcryoballoon 334 to expand therein. Concurrently, the expanded cryogenicgas proximally exits the interior of cryoballoon 334 via a space betweenshafts 324, 320 and outer shaft 316, as best shown in FIG. 3C. In anembodiment, a vacuum may be utilized to pull the expanded cryogenic gasout of the catheter although the vacuum is not required for the gas toexit. The expanded cryogenic gas travels proximally through proximalballoon neck 315 and within lumen 318 of outer shaft 316 for the lengthof catheter 306, and then exits catheter 306 via an arm 309 of hub 308.As shown in the cross-sectional view of FIG. 3D, cryotherapy shaft 324extends freely through, e.g., is not bonded to, arm 309 and thus theexpanded cryogenic gas may escape via an annular lumen or space 311defined between cryotherapy shaft 324 and arm 309. In another embodiment(not shown), cryotherapy shaft 324 may be bonded or otherwise coupled toone sidewall of outer shaft 316.

FIG. 6 illustrates another embodiment hereof in which the inflationfluid for the constraining balloon may be circulated in order to bettercontrol the temperature thereof. More particularly, an ablation assembly600 includes a cryoballoon 634 and a constraining balloon 636.Cryo-supply tube 624 and guidewire shaft 620 extend through outer shaft616 and into proximal balloon neck 615 of cryoballoon 634 as describedabove with respect to catheter 306. However, in this embodiment,constraining-supply tube 628 as well as an inflation fluid return orexhaust shaft 650 extend through outer shaft 616 and into an interior ofconstraining balloon 636 via proximal balloon neck 617 of constrainingballoon 636. Proximal bond 629 surrounds shafts 628, 650 and seals offthe interior of constraining balloon 636 from lumen 618 of outer shaft616. A continuous supply of inflation fluid enters the interior ofconstraining balloon 636 via constraining-supply tube 628 to inflate andexpand constraining balloon 636. The inflation fluid then exits theinterior of constraining balloon 636 via exhaust shaft 650 such that theinflation fluid within constraining balloon 636 may be continuouslycirculated. The continuous circulation allows for the inflation fluidwithin the interior of constraining balloon 636 to be maintained at awarmer temperature, which improves the ability of constraining balloon636 to protect non-targeted tissue from ablation because constrainingballoon 636 is prevented from cooling to a cryoablation temperature dueto heat transfer with cryoballoon 634. The relatively warmer temperaturemaintained in constraining balloon 636 due to the continuous circulationof inflation fluid also permits improved heat transfer from constrainingballoon 636 to cryoballoon 634 to better moderate the temperature of thecryotherapy as described herein.

FIG. 7 illustrates another embodiment hereof in which exhaust from thecryoballoon serves as the inflation fluid for the constraining balloonin order to simplify the construction of the catheter and reduce therequired number of lumens, which may also reduce an outer diameter ofthe catheter. More particularly, an ablation assembly 700 can include acryoballoon 734 and a constraining balloon 736. Cryo-supply tube 724 andguidewire shaft 720 extend through outer shaft 716 and into proximalballoon neck 715 of cryoballoon 734 as described above with respect tocatheter 306. However, in this embodiment, a U-shaped connector 752fluidly connects the interior of cryoballoon 734 and the interior ofconstraining balloon 736. The cryogenic agent is delivered intocryoballoon 734 and there is a pressure drop when the cryogenic agententers the interior of cryoballoon 734 and expands to gas. As thecryogenic agent expands into gas, cryoballoon 734 is expanded and theexhaust gas travels through U-shaped connector 752 and into constrainingballoon 736 to expand the constraining balloon. Although the temperatureof cryoballoon 734 ablates target tissue in contact with cryoballoon734, the exhaust gas that leaves cryoballoon 734 and fills constrainingballoon 736 can be approximately 20° C. to 50° C. warmer than thetemperature of cryoballoon 734. Thus, although the gas exhaust is stillcool, the temperature of constraining balloon 736 can remain above −5°C. such that thermal injury of non-targeted tissue adjacent toconstraining balloon 736 will not occur. In one embodiment (not shown),the length of U-shaped connector 752 may be increased such that thedistal loop extends further distally into blood flow that serves toadditionally warm the exhaust gas before it enters the interior ofconstraining balloon 736. The exhaust gas continues to flow throughproximal neck 717 of constraining balloon 736, past proximal bond 729,and proximally exits the catheter through an unsealed arm of the hub inthe same way as described above with respect to FIG. 3D.

In another embodiment hereof, the catheter may include two separateguidewire lumens for more controlled positioning of the ablationassembly. Two separate guidewire lumens also allow for two differenttypes of guidewires to be utilized for placement of the catheter. Forexample, a floppy-tipped guidewire and a stiff-tipped guidewire may bothbe useful in advancing the catheter through tortuous anatomy. Althoughonly one guidewire is required for positioning the catheter, bothguidewires are in place and may be utilized if required. For example, asshown in FIG. 8, FIG. 8A, and FIG. 8B, a dual balloon catheter 806includes an ablation assembly 800 at a distal end thereof. Ablationassembly 800 includes a cryoballoon 834 and a constraining balloon 836disposed adjacent, i.e., side-by-side, to cryoballoon 834. A cryo-supplytube 824 and a guidewire shaft 820A extend through an outer shaft 816and into a proximal balloon neck 815 of cryoballoon 834, in the mannerdescribed above with respect to catheter 306. Outer shaft 816 defines alumen 818 therethrough.

Guidewire shaft 820A defines a guidewire lumen 822A for receiving aguidewire 842A. However in this embodiment, in addition to aconstraining-supply tube 828 defining an inflation lumen 830, a secondinner guidewire shaft 820B extends through constraining balloon 836.Guidewire shaft 820B defines a guidewire lumen 822B extendingsubstantially the entire length of the catheter for accommodating asecond guidewire 842B. Outer shaft 816 has a proximal end 840 thatextends out of the patient and is coupled to a hub 808 and a distal end841 coupled to proximal necks 815, 817 of balloons 834, 836,respectively. Distal ends 819, 821 of balloons 834, 836, respectively,are coupled to guidewire shafts 820A, 820B, respectively. Guidewireshafts 820A, 820B have proximal ends (not shown) coupled to hub 808 anddistal ends that terminate distally of balloons 834, 836. Hub 808includes guidewire port 814A in fluid communication with guidewire lumen822A of guidewire shaft 820A and a guidewire port 814B in fluidcommunication with guidewire lumen 822B of guidewire shaft 820B. Inaddition, hub 808 includes a first inflation port 812 in fluidcommunication with inflation lumen 830 of constraining-supply tube 828and a second inflation port 810 in fluid communication with inflationlumen 826 of cryo-supply tube 824. Similar to proximal bond 329described above, a proximal bond 829 surrounds and seals off an interiorof balloon 834 from lumen 818 of outer shaft 816. At the site ofproximal bond 829, outer shaft 816 transforms from the annularconfiguration of FIG. 8A to a generally figure “8” configuration whichresembles balloon necks 815, 817.

FIG. 9, FIG. 9A, and FIG. 9B illustrate another embodiment hereof inwhich the catheter may include two separate guidewire lumens for morecontrolled positioning of the ablation assembly. In this embodiment, twoindividual balloon catheters 906A, 906B are coupled together via acoupler sleeve 960. An ablation assembly 900 is formed at the distal endof balloon catheters 906A, 908B, with a cryoballoon 934 disposed at thedistal end of balloon catheter 906A and a constraining balloon 936disposed at the distal end of balloon catheter 906B. The first ballooncatheter 906A includes an outer shaft 916A defining a lumen 918A. Acryo-supply tube 924 defining a lumen 926 and a guidewire shaft 920Adefining a guidewire lumen 922A for receiving a guidewire 942A bothextend through outer shaft 916A. Cryoballoon 934 disposed at the distalend of catheter 906A is inflated with a cryogenic agent as describedabove with respect to cryoballoon 334. The second balloon catheter 906Bincludes an outer shaft 916B and an inner guidewire shaft 920B defininga guidewire lumen 922B for receiving a guidewire 942B. In the coaxialcatheter construction of second balloon catheter 906B, guidewire shaft920B extends within outer shaft 916B such that an annular inflationlumen 918B is defined between an inner surface of outer shaft 916B andan outer surface of guidewire shaft 920B. Constraining balloon 936disposed at the distal end of catheter 906B is inflated via inflationfluid delivered through annular inflation lumen 918B. A first hub 908Ais coupled to first balloon catheter 906A and a second hub 908B iscoupled to second balloon catheter 906B. Hubs 908A, 908B includeguidewire ports 914A, 914B, respectively, in fluid communication withguidewire lumens 922A, 922B of guidewire shafts 920A, 920B and inflationports 910, 912 in fluid communication with inflation lumens 926, 918B ofcryo-supply tube 924 and outer shaft 916B, respectively. In thisembodiment, having two separate balloon catheters may simplify the bondarea between each catheter and its respective balloon since each outershaft is bonded to a single proximal balloon neck rather than twobifurcating proximal balloon necks as described with respect toembodiments described above.

Coupler sleeve 960 extends over a portion of catheters 916A, 916B tocouple them together and properly position balloons 934, 936 in parallelwithin a target artery. In an embodiment, coupler sleeve 960 has alength between 10 mm and 30 mm long. Coupler sleeve 960 may be formedfrom any suitable biocompatible material, including but not limited topolyethylene, polyethylene block amide copolymer (PEBA), polyamide,and/or combinations thereof, which can be laminated, blended,co-extruded, or processed according to another suitable method. Couplersleeve 960 may have a circular or oval cross-section as shown in FIG.9B, or may have a profile resembling the figure “8” to reduce theprofile thereof. In an embodiment, coupler sleeve 960 may be a removableseparate component and an operator may assemble separate ballooncatheters 906A, 906B into coupler sleeve 960. As a result, the operatormay select appropriate balloon sizes or types to best treat thetreatment site. For example, the operator may select a catheter having aconstraining balloon with a particular expanded outer diameter and/orlength in order to customize the size of the nominal treatmentarea/ablation pattern. Such customization is useful for accommodatingindividual anatomy of a patient. In another embodiment, coupler sleeve960 and balloon catheters 906A, 906B may be formed as a single, integralassembly.

In the embodiments of FIG. 8 and FIG. 9, the distal ends of thecryoballoon and the constraining balloon separately extend in a distaldirection and are not joined together. As such, in one embodiment, oneor more mechanisms may be utilized to couple the cryoballoon and theconstraining balloon together, which may prevent the balloons fromfolding over one another during deployment. Referring to FIG. 10, in oneembodiment, cryoballoon 834/934 and constraining balloon 836/936 arecoupled together via an adhesive 1062. In another embodiment shown inFIG. 11, an outer sheath 1164 may be used to hold cryoballoon 834/934and constraining balloon 836/936 adjacent to one another in aside-by-side configuration during deployment. In one embodiment, outersheath 1164 is an elastic tubular member which expands as thecryoballoon and the constraining balloon are inflated. Outer sheath 1164surrounds and constrains the cryoballoon and the constraining balloon tokeep them in an adjacent or side-by-side configuration. Outer sheath1164 is formed of a substantially noninsulative material which does notaffect ablation performed by the cryoballoon, such as polyurethane,PEBAX polymer, or silicone. In another embodiment, outer sheath 1164 isnot elastic. In yet another embodiment, outer sheath 1164 may compriseone or more annular segments (not shown) rather than a continuoustubular member that covers at least a portion of the cryoballoon and theconstraining balloon.

In yet another embodiment, outer sheath 1164 may be closed at the distalend thereof in order to form an outer inflatable balloon which surroundsand constrains cryoballoon 834/934 and constraining balloon 836/936. Inaddition to keeping cryoballoon 834/934 and constraining balloon 836/936in an adjacent side-by-side or generally parallel configuration, outersheath 1164 can occlude blood flow when inflated against the vesselwall. Occlusion of blood flow may be desirable since blood flow past acryogenic balloon may affect the desired ablation therapy pattern.

In another embodiment hereof, the ablation assembly includes one or moreprongs for deflecting the cryogenic balloon away from non-target tissuewithin a vessel. More particularly, FIG. 12 is a partially schematiccross-sectional view of an artery A having an ablation assembly 1200deployed therein. Ablation assembly 1200 includes a cryogenic balloon1234 for ablating tissue and a constraining element 1236 that positionscryogenic balloon 1234 within the artery. In this embodiment,constraining element 1236 is a pair of self-expanding prongs thatdeflect or offset contact of cryoballoon 1234 against the vessel wall.

FIG. 13 is a side view of an example of a catheter system for deliveringthe self-expanding prongs that deflect a cryoballoon away fromnon-target tissue of the vessel wall. More particularly, a ballooncatheter 1306 includes an outer shaft 1316 defining a lumen (not shown)and an inner guidewire shaft 1320 defining a guidewire lumen (not shown)for receiving a guidewire 1342. In the catheter construction of ballooncatheter 1306, a cryogenic inflation shaft (not shown in FIG. 13)similar to cryo-supply tube 324 extends through catheter 1306 forreceiving a cryogenic inflation medium to inflate cryogenic balloon1334. Cryoballoon 1334 is inflated with a cryogenic agent as describedabove with respect to cryoballoon 334, and expanded cryogenic gas orexhaust exits catheter 1306 via the space defined between an innersurface of outer shaft 1316 and the outer surfaces of guidewire shaft1320 and the cryogenic inflation shaft. A hub 1308 is disposed at theproximal end of catheter 1306. Hub 1308 includes an inflation port 1310in fluid communication with the inflation lumen of the cryogenicinflation shaft and a guidewire port 1314 in fluid communication withthe guidewire lumen of inner guidewire shaft 1320. An ablation assembly1300 includes a cryoballoon 1334 and a pair of self-expanding prongs1372A, 1372B disposed at the distal end of catheter 1306. Only one ofthe prongs 1372A, 1372B is shown in FIG. 13 and in FIGS. 13A, 13B, and14, which are described below.

As shown in FIG. 13A, a tubular sheath 1370 is disposed over catheter1306 (FIG. 13) and constrains the pair of self-expanding prongs 1372A,1372B into a reduced diameter suitable for delivery within avasculature. Prongs 1372A, 1372B are coupled to a push-pull wire 1378(FIG. 13), which proximally extends out of catheter 1306 and can bemanipulated by the operator. Push-pull wire 1378 is utilized fordistally advancing and proximally retracting prongs 1372A, 1372B withinsheath 1370. When distally advanced out of sheath 1370, prongs 1372A,1372B deploy to an expanded configuration shown in FIG. 13, FIG. 13B,FIG. 13C, FIG. 14, and FIG. 15. For clarity purposes, cryoballoon 1334is omitted from the side view and bottom/top view of FIG. 14 and FIG.15, respectively. Cryoballoon 1334 is pushed to one side of a vessel byprongs 1372A, 1372B which press against the opposite side of the arteryto result in a partial circumferential ablation pattern. Cryoballoon1334 is formed from a non-compliant or low-compliant material to preventit from expanding between prongs 1372A, 1372B and onto the vessel wall.For example, cryoballoon 1334 may be formed from nylon, PEBAX polymer,or polyethylene terephthalate (PET).

Referring to FIG. 14 and FIG. 15, each prong 1372A, 1372B includes aproximal segment 1376A, 1376B, a curved segment 1374A, 1374B, and adistal segment 1380A, 1380B. In one embodiment, each prong 1372A, 1372Bis a unitary structure formed out of a single or integral piece ofmaterial. In another embodiment, the curved segment 1374A, 1374B of eachprong is a separate component which may be the same material or adifferent material that is attached to the proximal and distal segmentsby any suitable manner known in the art such as for example welding,including resistance welding, friction welding, laser welding or anotherform of welding, soldering, using an adhesive, adding a connectingelement there between, or by another mechanical method. Prongs 1372A,1372B can be formed from shape memory materials such as a nitinol wire,and can be self-expanding. The nitinol wire may be solid or hollow andmay have a circular, oval, square, rectangular, or any other suitablecross-sectional shape.

During delivery, each prong 1372A, 1372B is constrained into asubstantially straight configuration within sheath 1370 and whenreleased from sheath 1370, each prong 1372A, 1372B assumes its preformedshape or deployed configuration that presses the outer surface of theballoon against the opposing vessel wall. More particularly, in thedeployed configuration, proximal segments 1376A, 1376B are relativelyshort and substantially straight segments that distally extend frompush-pull wire 1378. As shown in the bottom view of FIG. 15, proximalsegments 1376A, 1376B diverge in opposing radial directions to placeprongs 1372A, 1372B on opposing sides of cryogenic balloon 1334. Asshown in the side view of FIG. 14, proximal segments 1376A, 1376B extendwithin a plane parallel to the longitudinal axis of the vessel. Curvedsegments 1374A, 1374B distally extend from proximal segments 1376A,1376B and curve in a radial direction towards the vessel wall. Curvedsegments 1374A, 1374B operate to contact and push against the proximalportion of cryogenic balloon 1334 to deflect a portion of cryogenicballoon 1334 away from the vessel wall. Generally straight distalsegments 1380A, 1380B distally extend from curved segments 1374A, 1374Bin a direction parallel to the longitudinal axis of the vessel. Distalsegments 1380A, 1380B press and/or lodge prongs 1372A, 1372B against oneside of a vessel, while cryogenic balloon 1334 presses against theopposing side of the vessel.

In other embodiments, different configurations of self-expanding prongsthat deflect cryogenic balloon 1334 away from non-targeted tissue of thevessel wall can be used. For example, FIG. 16 shows prongs 1672A, 1672Bhaving distal ends that are connected via a V-shaped joining segment1682, and FIG. 17 shows prongs 1772A, 1772B having distal ends that areconnected with a rounded U-shaped joining segment 1782. Joining segments1682, 1782 may be integrally formed between the two prongs, or may be aseparate component coupled to the two prongs. Connecting the distal endsof the prongs can essentially form a single prong with improvedstability for deflecting a cryoballoon. Prongs 1872A, 1872B in FIG. 18are similar to prongs 1672A, 1672B but also include a diagonal supportsegment 1884 extending therebetween for stabilizing and/or strengtheningthe deflecting prong. Lastly, it will be understood by those of ordinaryskill in the art that alternative deployment mechanisms may be utilizedfor deploying the deflecting prongs. For example, referring to FIG. 19,each prong 1972A, 1972B may be coupled to a separate push-pull wire1978A, 1978B for individually controlling deployment of each prong.Separate deployment of each prong 1972A, 1972B provides selectivecontrol over the amount of the cryoballoon that is deflected away fromthe vessel wall, and therefore provides selective control over theablation therapy pattern. For example, only one of prongs 1972A, 1972Bmay be deployed for less constraining of the cryoballoon and thusablation occurring around a greater portion of the circumference of thevessel while both prongs 1972A, 1972B may be deployed for moreconstraining of the cryoballoon and thus ablation occurring around alesser portion of the circumference of the vessel. In anotherembodiment, the deployment of self-expanding prongs may be accomplishedand/or assisted by retraction of sheath 1370 as will be understood bythose of ordinary skill in the art.

Since blood flow past a cryogenic balloon may affect the desiredablation therapy pattern, any embodiment described herein may include anocclusion balloon or other occlusive device. The occlusive device may beplaced concentrically around the ablation assembly as described withrespect to the outer sheath of FIG. 11, or may be placed proximal to ordistal to the ablation assembly. Further, the occlusive device may beintegrally formed on the delivery catheter of the ablation assembly ormay be a separate device utilized with the delivery catheter of theablation assembly.

Some embodiments are described herein with respect to partialcircumferential ablation of vessel walls. However, in some applications,it may be desirable to perform full circumferential ablation of vesselwalls that is also non-continuous or helical. Non-continuous, fullcircumferential ablation can include forming two or more partialcircumferential ablations that collectively extend around the entirecircumference of the vessel wall. Helical, full circumferential ablationcan include forming one or more ablations that curve to extend aroundthe entire circumference of the vessel wall without being fullycircumferential in any single plane perpendicular to the vessel. Thenon-continuous or helical nature of these full circumferential ablationscan reduce structural changes to any one region of the vessels incomparison to other full circumferential ablations. It will beunderstood by those of ordinary skill in the art that embodiments hereoffor creating partial circumferential ablation patterns may also beutilized for creating non-continuous or helical full circumferentialablation patterns. For example, catheters having ablation assembliesdescribed herein may be longitudinally translated within a vessel androtated as desired in order to perform multiple, sequential partialcircumferential ablations which collectively extend around the entirecircumference of the vessel wall. In some embodiments, relatively shortballoons having lengths between 2 mm and 5 mm may be rotated and movedlongitudinally in a vessel to produce a non-continuous and helicalablation pattern.

EXAMPLES

1. A cryotherapeutic device, comprising:

-   -   an elongated shaft including a distal portion, the shaft        configured to locate the distal portion in an anatomical vessel;    -   a first balloon at the distal portion;    -   a first supply lumen along at least a portion of the shaft;    -   a first exhaust lumen along at least a portion of the shaft, the        first exhaust lumen fluidly connected to the first supply lumen        via the first balloon;    -   a second balloon at the distal portion fluidly separate from the        first supply lumen and the first exhaust lumen, the second        balloon configured to prevent the first balloon from        cryogenically cooling a full circumference of a wall of the        anatomical vessel in generally any plane perpendicular to a        length of the anatomical vessel;    -   a second supply lumen along at least a portion of the shaft; and    -   a second exhaust lumen along at least a portion of the shaft,        the second exhaust lumen fluidly connected to the second supply        lumen via the second balloon.

2. The cryotherapeutic device of example 1 wherein—

-   -   the first balloon is non-compliant or semi-compliant, and    -   the second balloon is compliant.

3. The cryotherapeutic device of example 1 wherein—

-   -   the first balloon is less than 10% compliant, and    -   the second balloon is between 50% and 100% compliant.

4. The cryotherapeutic device of example 1 wherein—

-   -   the second balloon includes a proximal portion and a distal        portion,    -   the second supply lumen includes an opening at one of the        proximal and distal portions of the second balloon, and    -   the second exhaust lumen includes an opening at the other of the        proximal and distal portions of the second balloon.

5. The cryotherapeutic device of example 1 wherein—

-   -   the cryotherapeutic device is configured to cryogenically cool a        portion of the wall of the anatomical vessel proximate the first        balloon when pressurized refrigerant is delivered to the first        balloon through the first supply lumen, expanded in the first        balloon, and exhausted from the first balloon through the first        exhaust lumen, and    -   the cryotherapeutic device is configured to warm the first        balloon when a heat-transfer fluid is delivered to the second        balloon through the second supply lumen, moved within the second        balloon, and exhausted from the second balloon through the        second exhaust lumen.

6. A method for treating a patient, comprising:

-   -   locating a distal portion of an elongated shaft of a        cryotherapeutic device within an anatomical vessel of the        patient;    -   delivering refrigerant to a first balloon of the cryotherapeutic        device at the distal portion;    -   expanding the refrigerant within the first balloon to cool the        first balloon;    -   cooling a portion of a wall of the anatomical vessel proximate        the first balloon; and    -   circulating a heat-transfer fluid through a second balloon of        the cryotherapeutic device proximate the first balloon and        fluidly separate from the first balloon to warm the first        balloon and to moderate the cooling of the portion of the wall        of the anatomical vessel.

7. The method of example 6 wherein circulating the heat-transfer fluidcauses a temperature of the first balloon to be between −10° C. and −40°C.

8. The method of example 6 further comprising contacting between 45° and225° of the wall of the anatomical vessel with the first balloon.

9. The method of example 6 further comprising—

-   -   semi- or non-compliantly expanding the first balloon with the        refrigerant; and    -   compliantly expanding the second balloon with the heat-transfer        fluid.

10. The method of example 6 further comprising using the second balloonto prevent the first balloon from cryogenically cooling a fullcircumference of the wall of the anatomical vessel in generally anyplane perpendicular to a length of the anatomical vessel.

11. A cryotherapeutic device, comprising:

-   -   a first catheter, including—        -   a first elongated shaft having a distal portion,        -   a first balloon at the distal portion of the first shaft,        -   a supply lumen along at least a portion of the first shaft,        -   an exhaust lumen along at least a portion of the first            shaft, the exhaust lumen fluidly connected to the supply            lumen via the first balloon;    -   a second catheter, including—        -   a second elongated shaft having a distal portion, and        -   a second balloon at the distal portion of the second shaft;            and    -   a coupler sleeve configured to be within an anatomical vessel        and to receive the first and second catheters in a parallel        arrangement.

12. The cryotherapeutic device of example 11, further comprising a thirdcatheter, wherein—

-   -   the third catheter includes—        -   a third elongated shaft having a distal portion, and        -   a third balloon at the distal portion of the third shaft,    -   the second balloon and the third balloon are configured to        expand to different sizes, and    -   the second and third catheters are interchangeable with respect        to the coupler sleeve.

13. The cryotherapeutic device of example 11 further comprising anexpandable outer sheath connected to the coupler sleeve, wherein thefirst and second balloons are configured to fit together within theexpandable outer sheath when the first and second catheters are withinthe coupler sleeve.

14. The cryotherapeutic device of example 11 wherein the cryotherapeuticdevice is configured to cryogenically cool a portion of a wall of theanatomical vessel proximate the first balloon when pressurizedrefrigerant is delivered to the first balloon through the first supplylumen, expanded in the first balloon, and exhausted from the firstballoon through the first exhaust lumen.

15. The cryotherapeutic device of example 11 wherein the second balloonis configured to prevent the first balloon from cryogenically cooling afull circumference of the wall of the anatomical vessel in generally anyplane perpendicular to a length of the anatomical vessel.

16. The cryotherapeutic device of example 11 wherein—

-   -   the first catheter includes a first guidewire lumen along at        least a portion of the first shaft and extending through the        first balloon, and    -   the second catheter includes a second guidewire lumen along at        least a portion of the second shaft and extending through the        second balloon.

17. A method for treating a patient, comprising:

-   -   locating a distal portion of a first elongated shaft of a first        catheter within an anatomical vessel of the patient;    -   delivering refrigerant to a first balloon of the first catheter        at the distal portion of the first shaft;    -   expanding the refrigerant within the first balloon to cool the        first balloon;    -   cooling a portion of a wall of the anatomical vessel proximate        the first balloon;    -   selecting a second catheter from a plurality of catheters based        on a size of the anatomical vessel and a size of a second        balloon of the second catheter;    -   locating a distal portion of a second elongated shaft of the        second catheter within the anatomical vessel proximate the first        distal portion of the first elongated shaft, the second balloon        being at the distal portion of the second elongated shaft; and    -   expanding the second balloon between the first balloon and the        wall of the anatomical vessel to prevent the first balloon from        cryogenically cooling a full circumference of the wall of the        anatomical vessel in generally any plane perpendicular to a        length of the anatomical vessel.

18. The method of example 17 wherein locating the distal portion of thefirst shaft and locating the distal portion of the second shaft aregenerally simultaneous.

19. The method of example 17 further comprising coupling the first andsecond catheters after selecting the second catheter.

20. The method of example 19 wherein coupling the first and secondcatheters includes introducing the first and second catheters into acoupler sleeve.

21. A cryotherapeutic device, comprising:

-   -   an elongated shaft including a distal portion, the shaft        configured to locate the distal portion in an anatomical vessel;    -   an elongated balloon at the distal portion;    -   a supply lumen along at least a portion of the shaft;    -   an exhaust lumen along at least a portion of the shaft, the        exhaust lumen fluidly connected to the supply lumen via the        balloon; and    -   an elongated, self-expanding prong at the distal portion,    -   wherein—        -   the balloon is configured to preferentially expand away from            the prong, and        -   the prong is configured to prevent the balloon from            cryogenically cooling a full circumference of a wall of the            anatomical vessel in generally any plane perpendicular to a            length of the anatomical vessel.

22. The cryotherapeutic device of example 21 wherein the balloon isnon-compliant or semi-compliant.

23. The cryotherapeutic device of example 21 wherein the balloon is lessthan 10% compliant.

24. The cryotherapeutic device of example 21 wherein—

-   -   the prong is a first prong,    -   the cryotherapeutic device further comprises a second prong, and    -   the first and second prongs are deployable independently or        together to change the size of a portion of the anatomical        vessel cryogenically cooled by the balloon.

25. The cryotherapeutic device of example 21 wherein—

-   -   the prong is a first prong,    -   the cryotherapeutic device further comprises a second prong, and    -   the first and second prongs are proximally connected to a        push/pull wire.

26. The cryotherapeutic device of example 25 wherein—

-   -   the first and second prongs are distally connected, and    -   the cryotherapeutic device further comprises a diagonal support        between the first and second prongs.

27. A method for treating a patient, comprising:

-   -   locating a distal portion of an elongated shaft of a catheter        within an anatomical vessel of the patient;    -   pressing an elongated prong at the distal portion of the shaft        against a first portion of a wall of the anatomical vessel,    -   delivering refrigerant to a balloon of the catheter at the        distal portion of the shaft to cool the balloon and to        preferentially expand the balloon in a radial direction away        from the prong; and    -   cooling a second portion of the wall of the anatomical vessel        proximate the balloon, wherein the prong urges the balloon        against the second portion of the wall of the anatomical vessel        and spaces the balloon apart from the first portion of the wall        of the anatomical vessel.

28. The method of example 27 wherein the first and second portions ofthe wall of the anatomical vessel are at generally opposite sides of thewall of the anatomical vessel.

29. The method of example 27 wherein delivering refrigerant to theballoon non-compliantly or semi-compliantly expands the balloon.

30. The method of example 27 further comprising controlling deflectionof the prong to control the size of the second portion of the wall ofthe anatomical vessel.

31. The method of example 27 further comprising selecting a number ofelongated prongs at the distal portion of the shaft to press against thefirst portion of the wall of the anatomical vessel to control the sizeof the second portion of the wall of the anatomical vessel.

CONCLUSION

While various embodiments according to the present technology have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons skilled in the relevant art that various changes inform and detail can be made therein without departing from the spiritand scope of the invention. Thus, the breadth and scope of the presentinvention should not be limited by any of the above-describedembodiments. It will also be understood that each feature of eachembodiment discussed herein, and of each reference cited herein, can beused in combination with the features of any other embodiment. Allpatents and publications discussed herein are incorporated by referenceherein in their entirety.

Where the context permits, singular or plural terms may also include theplural or singular terms, respectively. Moreover, unless the word “or”is expressly limited to mean only a single item exclusive from the otheritems in reference to a list of two or more items, then the use of “or”in such a list is to be interpreted as including (a) any single item inthe list, (b) all of the items in the list, or (c) any combination ofthe items in the list. Additionally, the terms “comprising” and the likeare used throughout the disclosure to mean including at least therecited feature(s) such that any greater number of the same feature(s)and/or additional types of other features are not precluded. It willalso be appreciated that various modifications may be made to thedescribed embodiments without deviating from the present technology.Further, while advantages associated with certain embodiments of thepresent technology have been described in the context of thoseembodiments, other embodiments may also exhibit such advantages, and notall embodiments need necessarily exhibit such advantages to fall withinthe scope of the present technology. Accordingly, the disclosure andassociated technology can encompass other embodiments not expresslyshown or described herein.

We claim:
 1. A cryotherapeutic device, comprising: an elongate shafthaving a distal end portion, wherein the shaft is configured to locateits distal end portion at a treatment site within an anatomical lumen ofa human patient; a first balloon at the distal end portion of the shaft,wherein the first balloon includes a flexible wall defining anexpandable interior volume; a first supply lumen carried by the shaft; afirst exhaust lumen carried by the shaft, wherein the first exhaustlumen is fluidly connected to the first supply lumen via the interiorvolume of the first balloon; a second balloon at the distal end portionof the shaft, wherein the second balloon includes a flexible walldefining an expandable interior volume fluidly separate from the firstsupply lumen and from the first exhaust lumen, and wherein the secondballoon is configured to prevent the first balloon from contacting afull circumference of a wall of the anatomical lumen in any planeperpendicular to a length of the anatomical lumen; a second supply lumencarried by the shaft; and a second exhaust lumen carried by the shaft,wherein the second exhaust lumen is fluidly connected to the secondsupply lumen via the interior volume of the second balloon, and whereinthe respective interior volumes of the first and second balloons arenon-overlapping.
 2. The cryotherapeutic device of claim 1 wherein: thewall of the first balloon is non-compliant or semi-compliant; and thewall of the second balloon is compliant.
 3. The cryotherapeutic deviceof claim 1 wherein: the wall of the first balloon is less than 10%compliant; and the wall of the second balloon is between 50% and 100%compliant.
 4. The cryotherapeutic device of claim 1 wherein: the secondsupply lumen includes an opening at a proximal portion of the interiorvolume of the second balloon; and the second exhaust lumen includes anopening at a distal portion of the interior volume of the secondballoon.
 5. The cryotherapeutic device of claim 1 wherein: thecryotherapeutic device is configured to cryogenically cool a firstportion of the wall of the anatomical lumen via the wall of the firstballoon when pressurized refrigerant is delivered to the interior volumeof the first balloon through the first supply lumen, expanded in theinterior volume of the first balloon, and exhausted from the interiorvolume of the first balloon through the first exhaust lumen; and thecryotherapeutic device is configured to warm a second portion of thewall of the anatomical lumen via the wall of the second balloon when aheat-transfer fluid is delivered to the interior volume of the secondballoon through the second supply lumen, moved within the interiorvolume of the second balloon, and exhausted from the interior volume ofthe second balloon through the second exhaust lumen.
 6. Thecryotherapeutic device of claim 1 wherein the first balloon and thesecond balloon are configured to be disposed in parallel at thetreatment site.
 7. The cryotherapeutic device of claim 1 wherein thefirst balloon and the second balloon are coextruded.
 8. Thecryotherapeutic device of claim 1 wherein the wall of the first balloonincludes polyethylene block amide copolymer (PEBA) or nylon.
 9. Thecryotherapeutic device of claim 8 wherein the wall of the second balloonincludes polyurethane or silicone.
 10. The cryotherapeutic device ofclaim 1 wherein the wall of the first balloon and the wall of the secondballoon are made of different materials.
 11. The cryotherapeutic deviceof claim 1 wherein the first balloon and the second balloon areconfigured to be disposed side-by-side at the treatment site.
 12. Amethod for treating a patient, the method comprising: locating a distalend portion of an elongate shaft of a cryotherapeutic device at atreatment site within an anatomical lumen of the patient; supplyingrefrigerant to a first balloon of the cryotherapeutic device at thedistal end portion of the shaft; expanding the refrigerant within aninterior volume defined by a flexible wall of the first balloon; coolinga first portion of a wall of the anatomical lumen via the wall of thefirst balloon; supplying heat-transfer fluid to a second balloon of thecryotherapeutic device at the distal end portion of the shaft; flowingthe heat-transfer fluid through an interior volume defined by a flexiblewall of the second balloon, wherein the respective interior volumes ofthe first and second balloons are non-overlapping while flowing theheat-transfer fluid through the interior volume of the second balloon;and warming a second portion of the wall of the anatomical lumen via thewall of the second balloon, wherein a plane perpendicular to a length ofthe anatomical lumen intersects the first balloon, the second balloon,the first portion of the wall of the anatomical lumen, and the secondportion of the wall of the anatomical lumen while cooling the firstportion of the wall of the anatomical lumen and while warming the secondportion of the wall of the anatomical lumen.
 13. The method of claim 12wherein the first portion of the wall of the anatomical lumenencompasses between 45° and 225° of a circumference of the anatomicallumen.
 14. The method of claim 12, further comprising: semi- ornon-compliantly expanding the first balloon with the refrigerant; andcompliantly expanding the second balloon with the heat-transfer fluid.15. The method of claim 12 wherein the second balloon prevents the firstballoon from contacting a full circumference of the wall of theanatomical lumen in any plane perpendicular to the length of theanatomical lumen while cooling the first portion of the wall of theanatomical lumen and while warming the second portion of the wall of theanatomical lumen.
 16. The method of claim 12 wherein flowing theheat-transfer fluid through the interior volume of the second balloonincludes continuously circulating the heat-transfer fluid through theinterior volume of the second balloon while warming the second portionof the wall of the anatomical lumen.
 17. The method of claim 12 whereincooling the first portion of the wall of the anatomical lumen andwarming the second portion of the wall of the anatomical lumen includecooling the first portion of the wall of the anatomical lumen andwarming the second portion of the wall of the anatomical lumen while thefirst and second balloons are disposed in parallel at the treatmentsite.
 18. The method of claim 12 wherein cooling the first portion ofthe wall of the anatomical lumen and warming the second portion of thewall of the anatomical lumen include cooling the first portion of thewall of the anatomical lumen and warming the second portion of the wallof the anatomical lumen while the first and second balloons are disposedside-by-side at the treatment site.
 19. The method of claim 12 whereinwarming the second portion of the wall of the anatomical lumen preventsthe first balloon from contacting a full circumference of the wall ofthe anatomical lumen in any plane perpendicular to the length of theanatomical lumen.